HEATING CIRCUIT

The library provides modules for evaluating 4 types of hydraulic circuits, where, based on Table C.1 of the standard, for each circuit it is identified which type of emission system to use and the type of control. as defined below:

Code	Module	Emitters	Control
C2	Constan mass flow rate and varying water temperature	Radiators and Panels	Heating curve, mixing valvew and variable generation temperature
C3	Varying mass flow (constant temperature)	Radiators, Panels, Heating coils	Thermostatic valve, flow rate control with two way valve
C4	ON-OFF and varying temperature	Radiators and Panels	On-Off control
C5	Varying heat exchange	Fan-coil, heating coils	emitters with on-off blower and continuos circulation 3 way by-pass valve control

All modules allow the us of a mixing valve to allow different temperatures in the different circuits. A distinction is made between: - the emitter tmperature and flow rate; - the circuit temperature and flow rate;

They differ where there is a mixing or by-pass 3 way valve in the circuit.

System type and input parameters

C2 - constant mass flow rate and varying water temperature

This conffiguration is for sample heating circuit with varying temperature and constant flow, with mixing valve.

Figure 1: System C2 - Example of heating circuit with varying temperature and constant flow, with mixing valve.

The application and possible control parameters to be used are:

System Application
Radiators
Heating Panels

Control Parameters
Heating curve
flow/return Δθ

The circuit can have a mixing valve or having a different control on boiler size (ex. climatic heating curve).

Inputs required

Constants

Water specific heat - cw: 1.16 kWh/m3K

Product data:

Parameter	Symbol	Unit	Default	Accetable	Description
Nominal emitted power	ΦH_em_n	kW	-	0.8..4 * heat load	Manufacturer's specified heat output in kilowatts (kW) under standard operating conditions
Nominal delta T (Δθ) air	ΔθH_em_air	°C	-	1..70	Standard temperature difference used for designing and evaluating HVAC systems, typically between the water entering and leaving the system, and the air entering and leaving the system.
Emitter exponent	nH_em	-	-	1...1.5	The emitter exponent is a value that defines the relationship between flow rate and pressure for an emitter

System data

if a mixing valve is used, the variable MIX_EM == True.

Process control data

Parameter	Symbol	Unit	Default	Accetable	Description
Design nominal delta T water (inlet-outlet)	ΔθH_em_n	°C	-	-	Nominal difference between the hot water supply temperature and the return water temperature in a heating system, depends on the typy of emitter, eg. Radiator: 20 (70-50), Heating floor 5 (43-38), etc.
Mixing valve temperature overhead	ΔθH_em_mix_sahz_i	°C	-	-	Temperature overhead of the mixing valve

Operating condition

These values can be obtained simulating the thermal zone using the module iso 52016 of the library.

Parameter	Symbol	Unit	Default	Accetable	Description
Internal temperature	θint	°C	-	0-45	Indoor operative temperature of the thermal zone, it is the T_op(°C) calcualted from the module 52016
Emitter heat output	QH_em_i_out	kWh	-	-	energy that sould be provided by the emission system to make up for energy need of the building. Pratically considering the energy path it si equal to the energy need of the building minus the system recoverable losses
Operating time	tH_em_i	h	1	-	Operating time of the system, generally in hours
Maximum distribution water temperature	θH_nod_out	°C	-	-	it is the maximum temperature of the ditribution system, this values depends on the type of applied control. If MIX_VALVE == False, this value is equal to the minimum of the emitter temperature θH_em_flw_min

C3 - varying mass flow rate and constant water temperature

This configuration is for sample heating circuit with varying mass flow rate and constant water temperature.

Figure 1: System C3_1 - Example of sample heating circuit varying mass flow rate.

Figure 1: System C3_1 - Example of sample heating circuit with series control (AHU coil).

The application and possible control parameters to be used are:

System Application
Radiators with thermostatic valve
AHU coil with series control
Panels with PID control

Control Parameters
Maximum flow/return Δθ
Maximum flow temperature
Target return temperature

Inputs required

Constants

Water specific heat - cw: 1.16 kWh/m3K

Product data:

Parameter	Symbol	Unit	Default	Accetable	Description
Nominal emitted power	ΦH_em_n	kW	-	0.8..4 * heat load	Manufacturer's specified heat output in kilowatts (kW) under standard operating conditions
Nominal delta T (Δθ) air	ΔθH_em_air	°C	-	1..70	Standard temperature difference used for designing and evaluating HVAC systems, typically between the water entering and leaving the system, and the air entering and leaving the system.
Emitter exponent	nH_em	-	-	1...1.5	The emitter exponent is a value that defines the relationship between flow rate and pressure for an emitter

System data

if a mixing valve is used, the variable MIX_EM == True.

Process control data

Parameter	Symbol	Unit	Default	Accetable	Description
Design nominal delta T water (inlet-outlet)	ΔθH_em_n	°C	-	-	Nominal difference between the hot water supply temperature and the return water temperature in a heating system, depends on the typy of emitter, eg. Radiator: 20 (70-50), Heating floor 5 (43-38), etc.
Mixing valve temperature overhead	ΔθH_em_mix_sahz_i	°C	-	-	Temperature overhead of the mixing valve
Target return temperature	θH_em_ret_req_sahz_i	°C	-	-	Desired return temperature of the emission circuit
Maximum flow/return Δθ	ΔθH_em_w_max_sahz_i	°C	-	-	Maximum flow/return temperature difference of the emission circuit
Maximum flow temperature	θH_em_flw_max_sahz_i	°C	-	-	Maximum flow temperature of the emission circuit

Operating condition

These values can be obtained simulating the thermal zone using the module iso 52016 of the library.

Parameter	Symbol	Unit	Default	Accetable	Description
Internal temperature	θint	°C	-	0-45	Indoor operative temperature of the thermal zone, it is the T_op(°C) calcualted from the module 52016
Emitter heat output	QH_em_i_out	kWh	-	-	energy that sould be provided by the emission system to make up for energy need of the building. Pratically considering the energy path it si equal to the energy need of the building minus the system recoverable losses
Operating time	tH_em_i	h	1	-	Operating time of the system, generally in hours
Maxium distribution water temperature	θH_nod_out	°C	-	-	it is the maximum temperature of the ditribution system, this values depends on the type of applied control. If MIX_VALVE == False, this value is equal to the minimum of the emitter temperature θH_em_flw_min

C4 - Intermittent flow rate module (ON-OFF)

This configuration is for sample heating circuit with intermittent flow rate and constant water temperature.

Figure 1: System C4 - Example of sample heating circuit with intermittent flow rate module (ON-OFF).

The application and possible control parameters to be used are:

System Application
ON-OFF zone control
ON-OFF room control

Control Parameters
Nominal Δθ (flow rate)
Target load factor

Constants

Water specific heat - cw: 1.16 kWh/m3K

Product data:

Parameter	Symbol	Unit	Default	Accetable	Description
Nominal emitted power	ΦH_em_n	kW	-	0.8..4 * heat load	Manufacturer's specified heat output in kilowatts (kW) under standard operating conditions
Nominal delta T (Δθ) air	ΔθH_em_air	°C	-	1..70	Standard temperature difference used for designing and evaluating HVAC systems, typically between the water entering and leaving the system, and the air entering and leaving the system.
Emitter exponent	nH_em	-	-	1...1.5	The emitter exponent is a value that defines the relationship between flow rate and pressure for an emitter

System data

if a mixing valve is used, the variable MIX_EM == True.

Process control data

Parameter	Symbol	Unit	Default	Accetable	Description
Design nominal delta T water (inlet-outlet)	ΔθH_em_n	°C	-	-	Nominal difference between the hot water supply temperature and the return water temperature in a heating system, depends on the typy of emitter, eg. Radiator: 20 (70-50), Heating floor 5 (43-38), etc.
Desired load factor	βH_em_req_sahz_i	%	-	-	Desired load factor with ON/OFF control
Set flow temperature	θH_em_flw_set	°C	-	-	Set flow temperature for the heating circuit

Operating condition

These values can be obtained simulating the thermal zone using the module iso 52016 of the library.

Parameter	Symbol	Unit	Default	Accetable	Description
Internal temperature	θint	°C	-	0-45	Indoor operative temperature of the thermal zone, it is the T_op(°C) calcualted from the module 52016
Emitter heat output	QH_em_i_out	kWh	-	-	energy that sould be provided by the emission system to make up for energy need of the building. Pratically considering the energy path it si equal to the energy need of the building minus the system recoverable losses
Operating time	tH_em_i	h	1	-	Operating time of the system, generally in hours
Maxium distribution water temperature	θH_nod_out	°C	-	-	it is the maximum temperature of the ditribution system, this values depends on the type of applied control. If MIX_VALVE == False, this value is equal to the minimum of the emitter temperature θH_em_flw_min

C5 - Constant flow rate and variable heat exchange

Figure 1: System C5-1 - Example of sample heating circuit with varying heat exchange

Figure 1: System C4 - Example of sample heating circuit with three way by-pass control.

The application and possible control parameters to be used are:

System Application
ON-OFF zone control
ON-OFF room control

Control Parameters
Nominal Δθ (flow rate)
Target load factor

Constants

Water specific heat - cw: 1.16 kWh/m3K

Product data:

Parameter	Symbol	Unit	Default	Accetable	Description
Nominal emitted power	ΦH_em_n	kW	-	0.8..4 * heat load	Manufacturer's specified heat output in kilowatts (kW) under standard operating conditions
Nominal delta T (Δθ) air	ΔθH_em_air	°C	-	1..70	Standard temperature difference used for designing and evaluating HVAC systems, typically between the water entering and leaving the system, and the air entering and leaving the system.
Emitter exponent	nH_em	-	-	1...1.5	The emitter exponent is a value that defines the relationship between flow rate and pressure for an emitter

System data

if a mixing valve is used, the variable MIX_EM == True.

Process control data

Parameter	Symbol	Unit	Default	Accetable	Description
Design nominal delta T water (inlet-outlet)	ΔθH_em_n	°C	-	-	Nominal difference between the hot water supply temperature and the return water temperature in a heating system, depends on the typy of emitter, eg. Radiator: 20 (70-50), Heating floor 5 (43-38), etc.
Target load factor	βH_em_req_sahz_i	%	-	-	Desired load factor with ON/OFF control
Minimum flow temperature	θH_em_flw_min_sahz_i	°C	-	-	Minimum flow temperature of the emission circuit for a zone i
Set flow temperature	θH_em_flw_set	°C	-	-	Set flow temperature for the heating circuit

Operating condition

These values can be obtained simulating the thermal zone using the module iso 52016 of the library.

Parameter	Symbol	Unit	Default	Accetable	Description
Internal temperature	θint	°C	-	0-45	Indoor operative temperature of the thermal zone, it is the T_op(°C) calcualted from the module 52016
Emitter heat output	QH_em_i_out	kWh	-	-	energy that sould be provided by the emission system to make up for energy need of the building. Pratically considering the energy path it si equal to the energy need of the building minus the system recoverable losses
Operating time	tH_em_i	h	1	-	Operating time of the system, generally in hours
Maxium distribution water temperature	θH_nod_out	°C	-	-	it is the maximum temperature of the ditribution system, this values depends on the type of applied control. If MIX_VALVE == False, this value is equal to the minimum of the emitter temperature θH_em_flw_min

Outputs

The follwing outputs are calculated for all configurations:

Parameter	Symbol	Unit	Default	Accetable	Description
Temperature of the flow (IN) circuit	θH_ecr_flw	°C	-	-	temperature of the circuit at the flow point - water inlet
Temperature of the return (OUT) circuit	θH_ecr_ret	°C	-	-	temperature of the circuit at the return point - water outlet
Flow rate of the circuit	V_H_cr	m3/h	-	-	Flow rate of the circuit
Distribution flow temperture	θH_dis_flw	°C	-	-	temperature of the distribution circuit - water inlet
Distribution return temperture	θH_dis_ret	°C	-	-	temperature of the distribution circuit - water outlet
Emission Load Factor	βH_em	-	-	-	Ratio between the average emitter power and the nominal emitter power
Minimu required flow temperature	θH_em_flw_min	°C	-	-	Minimum required flow temperature of the emitter